TY - JOUR

T1 - Magnetotail magnetic flux monitoring based on simultaneous solar wind and magnetotail observations

AU - Shukhtina, M. A.

AU - Gordeev, E. I.

AU - Sergeev, V. A.

AU - Tsyganenko, N. A.

AU - Clausen, L. B. N.

AU - Milan, S. E.

PY - 2016/9

Y1 - 2016/9

N2 - The magnetotail magnetic flux (MTF) is an important global variable to describe the magnetospheric state and dynamics. Existing methods of MTF estimation on the basis of the polar cap area, inferred from observations of global auroras and field-aligned currents, do not allow benchmarking due to the absence of a gauge for comparison; besides, they rarely allow a systematic nearly real time MTF monitoring. We describe three modifications (F-0, F-1, and F-2) of the method to calculate the MTF, based on simultaneous spacecraft observations in the magnetotail and in the solar wind, suitable for real-time MTF monitoring. The MTF dependence on the solar wind parameters and the observed tail lobe magnetic field is derived from the pressure balance conditions. An essential part of this study is the calibration of our approximate method against global 3-D MHD simulations and the empirical T14 magnetospheric field model. The calibration procedure provides all variables required to evaluate F-0, F-1, and F-2 quantities and, at the same time, computes the reference MTF value through any tail cross section. It allowed us to extend the method to be used in the near tail, investigate its errors, and define the applicability domain. The method was applied to Cluster and THEMIS measurements and compared with methods of polar cap area calculation based on IMAGE and AMPERE observations. We also discuss possible applications and some recent results based on the proposed method.

AB - The magnetotail magnetic flux (MTF) is an important global variable to describe the magnetospheric state and dynamics. Existing methods of MTF estimation on the basis of the polar cap area, inferred from observations of global auroras and field-aligned currents, do not allow benchmarking due to the absence of a gauge for comparison; besides, they rarely allow a systematic nearly real time MTF monitoring. We describe three modifications (F-0, F-1, and F-2) of the method to calculate the MTF, based on simultaneous spacecraft observations in the magnetotail and in the solar wind, suitable for real-time MTF monitoring. The MTF dependence on the solar wind parameters and the observed tail lobe magnetic field is derived from the pressure balance conditions. An essential part of this study is the calibration of our approximate method against global 3-D MHD simulations and the empirical T14 magnetospheric field model. The calibration procedure provides all variables required to evaluate F-0, F-1, and F-2 quantities and, at the same time, computes the reference MTF value through any tail cross section. It allowed us to extend the method to be used in the near tail, investigate its errors, and define the applicability domain. The method was applied to Cluster and THEMIS measurements and compared with methods of polar cap area calculation based on IMAGE and AMPERE observations. We also discuss possible applications and some recent results based on the proposed method.

KW - magnetotail

KW - magnetic flux

KW - STEADY MAGNETOSPHERIC CONVECTION

KW - SUBSTORM PLASMA SHEET

KW - POLAR-CAP AREA

KW - BIRKELAND CURRENTS

KW - IONOSPHERE SYSTEM

KW - BOUNDARY MOTION

KW - IMAGE FUV

KW - FIELD

KW - CONFIGURATION

KW - SIMULATION

U2 - 10.1002/2016JA022911

DO - 10.1002/2016JA022911

M3 - статья

VL - 121

SP - 8821

EP - 8839

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 0148-0227

IS - 9

ER -